Figure 1

Steps to tie a parallel sliding knot with alternating post 1: a simple knot is tied around the vessel 2: by pulling on the yellow strand the knot is reversed in a slip knot around the blue strand that from now on act as “post” 3: another loop is formed around the post forming a “half-hitch knot” also called “parallel sliding knot” 4: the procedure is then repeated, but now using the yellow strand as a post (alternating the post) 5: the completed knot : parallel sliding knot on alternating post.